Methods of producing a 1,2-diol by reacting an olefin with an aqueous hydrogen peroxide solution in formic acid or acetic acid to synthesize an epoxide and then by hydrolyzing the epoxide have been known for a long time (Organic Syntheses, Coll. Vol. 3, 217-219 (1955), J. Am. Chem. Soc., 67, 1786-1788 (1945), etc.) The methods require multi-step operations after the reactions, such as removing the solvent, reacting with an aqueous sodium hydroxide solution, and neutralizing with hydrochloric acid.
Another method of producing a 1,2-diol from an olefin via an epoxide by using peracetic acid as an oxidizing agent has been known (JP-A-4-41449). However, the method has problems such as corrosion of a reaction vessel, treatment of by-product acetic acid, etc.
In view of overcoming the problems by using an appropriate catalyst, methods of producing a 1,2-diol from an aqueous hydrogen peroxide and an olefin in one step using a tungsten complex catalyst have been reported (J. Chem. Soc., 1949, 2988-3000, J. Am. Oil Chem. Soc., 44, 316-320 (1967), Tetrahedron Lett., 29, 823-826 (1988), etc.) However, since the diol thus produced can be further oxidized, a ketone or a carboxylic acid is inevitably generated as a by-product.
Though attempts have been made to improve the 1,2-diol selectivity by tuning the reaction conditions (EP 146374; Synthesis, 1989, 295-297, etc.), the methods use highly-toxic benzene as a solvent and require complicated operations for isolating the product such as extraction using a 30% aqueous sulfuric acid solution and neutralization using a base.
Reactions between an olefin and an aqueous hydrogen peroxide using a solid catalyst such as TS-1 and MCM-41, which can be easily removed by filtration and reused, have recently been reported (J. Cat., 145, 151-158 (1994); Chem. Commun., 1998, 325-326; J. Cat., 189, 40-51 (2000), etc.) Though these reactions provide improved methods with respect to the operations, the reactions form a large amount of an epoxide or a ketone in addition to the desired 1,2-diol product, resulting in poor yield and low selectivity of the 1,2-diol. Thus, the development of a method capable of producing a 1,2-diol with high efficiency and high selectivity by a simple operation, using a catalyst that is easily recovered and reused without using a strong acid and a strong base causing the corrosion of a reaction vessel, has been strongly demanded.